Simulated air-speed indicating means for aviation ground trainers



J1me 1950 c. K. WILKINSON ETAL 2,510,161

MSIIULATED AIR SPEED INDICATING MEANS FOR AVIATION GROUND TRAINERS Filed Dot. 7, 1944 2 Sheets$heet 1 I H0 .52 20- i CLAUDE K.WILYKINSON REEVE C.MOREHOUSE June 6, 1 950 c. K. WILKINSON ETAL 2,510,151

SIMULATED AIR SPEED INDICATING MEANS FOR AVIATION GROUND TRAINERS Filed Oct. 7, 1944 2 Sheets-Sheet 2 GOPILOT msTRuusNT PANEL 'V A T 4 1 l. 34 PILOTS msT. PANEL v 44 rm v so msrnucrons ossx FIG. 2

PILOTS PANEL 52 RELAY PANEL GROUND TRAINER T OOPILOTS INSTRUMENT PANEL INSTRUOTORS DESK {72 [IE] [El F-Il 3 FIG. 3 ZJ CLAUDE K. WILKINSON REEVE G. MOREHOUSE Patented June 6, 1950 SIMULATED AIR-SPEED INDICATIN G MEANS FOR AVIATION GROUND TRAINERS Claude K. Wilkinson and Reeve C. Morehouse, United States Navy Application October 7, 1944, Serial No.'557,733

12 Claims.

(Granted under the act of March amended April 30, 1928; 370 O. G. 757) This invention pertains to indicators and more especially to means for indicating air speed in response to the manipulation of the controls of ground trainers.

The ground or synthetic trainer is designed to give the student pilot experience in reading flight instruments such as are employed on the instrument panel of a plane, the instruments being linked up with the various controls in the trainer to give a response on the face of the instruments for a given movement of the controls, which corresponding instruments in actual flight would give with similar movement of the controls during flight. As heretofore designed instruments forthis purpose in the ground trainer have been actuated by a combination of mechanical and pneumatic means.

It is an object of the present invention to provide an air speed indicator for use on the panel board of a ground trainer which is electrically operated in response to the controls of a ground trainer to simulate flight conditions, which is simple in design and which may readily be installed in existing trainers without undue change therein. v 4

As illustrated herein, three speed indicating instruments are employed, one for the pilot, one for the co-pilot and one for the instructor. Invention resides in a motor-generator combination in which the aforesaid instruments are con-- nected to the output side of the generator and are calibrated to indicate air speed which is proportional to the voltage in the output side oi the generator, means operable to vary the input to the motor, thereby to vary the output of the generator, and means automatically actuated in response tothe attitude of the trainer to efiect variation of the aforesaid means thereby to cause the instruments to read air speeds which will correspond to the reading of similar instruments in a plane under similar conditions during actual flight. The ground trainer is provided with simulated throttles and in accordance with the invention, there is also means for varying the input to the motor in response to the throttle opening to cause the instruments to indicate air speed corresponding to the response of an actual plane under similar throttle openings in flight. Various other factors efiect the speed of a plane for a given throttle opening and one of these is the lowering and raising of floats or of landing gear as it takes off or comes in for a landing. Levers are provided in the trainer for simulating the manipulation of the floats or landing gear and in order that the student may see justwhat efiect the lowering and raising of his landing gear has upon the reading of hisair speed instruments, and so that he may adjust the throttle to take care of any decrease in landing speed due to the lowering of the floats or landing gear, there is means connected to the output side of the generator operableby the aforesaid lever to place a resistance in the circuit which causes the air speed instrument to show a decrease in air speed corresponding to the actual decrease in air speed caused by the lowering of landing gear or of floats in a plane in actual flight. While on the ground and while climbing to normal flight level, the aforesaid circuit will cause the instruments to show air speeds greater than is actually the case since there is a lag 'due to water and ground resistance. To avoid this and to simulate the lag incident to take off and climb to stabilized flight the circuit is altered by a manual switch provided for this purpose and means is simultaneously placed in the circuit which may be manually actuated to cause the instruments to simulate the lag in speed incident to take ofi which would normally be evident in an actual plane. To this end and in accordance with yet another feature of the invention, there is connected to'the output side of the generator, a variable resistance arranged to be manually actuated by an instructor to cause the instruments to simulate the air speed of the plane from the time when the plane starts from rest until it leaves the ground and acquires stabilized flight conditions.

A description of the invention will now be set forth in detail with reference to the accompanying drawing; in which:

Fig. 1 is a diagrammatic lay-out of the instruments and electrical circuit which embodies my invention.

Fig. 2 is a diagrammatic lay-out of the wiring and instrument panels; and Fig. 3 is a diagrammatic showing of a ground trainer and instructors desk.

Referring to Figs. 1 and. 2 there is shown diagrammatically three electrical instruments 42, 44 and 46 which are installed in a ground trainer system, the instruments being positioned on the instrument panels for the pilot, co-pilot and instructor Fig. 2 and being calibrated in units of air speed. The instruments are energized by cur rent from a generator [2 whose field winding 2d Fig. 1 is maintained substantially constant by connecting it directly across supply lines 16 and. N3, the latter being connected to a source of l10-v. direct current. The armature 25 of the During simulated flight, it is desirable to cause the electric instruments 42, 44 and :46-ito;simu-- late actual air speed instruments in response'to actual plane conditions, that is, for changes in...

the attitude of the plane, variations in the throt tle opening and the employxiofzone:or.more.-ene.- 1o;i gines. If it is assumed that a plane is -fiying at constant throttle opening, andthe .controlsareoperated to cause the nose of 'the plane to-tilt'ii up as for climbing, it is evident that there will be a drop in air speed which will.registeronthe air speed instrument by movement of the pointer on the instrument to a lower reading. If the pilot is acutely aware of the meaning andlie'liect' of the drop in the air speed as indicated by'-his air speed instrument, he will immediately be warned therebyi that' to maintain? way; that is: tobmaintain the speedi'requisitetnto climbing. he: must rincrease'rhis throttle opening otherwiseiqhe'; mayxloose"speedf-sor rapidly that thetplan'e: may;

stall-and fall "into'a spin; This loss in airspeed:

du'e'toarclimb issimul'atediint the :ground trainer: onithe instruments '42; 44 rand-:46 :rby; inserting. "a:' rheostat i60',*which" is Simply'aWariableresistance; in-serieswith thearmatureiilzpf the?motor H] by Way? of conductors "58'rand ifi2. The; resistanceioi we the trheostat 60" isautomati'cally; varied .bya the; angular rposition of "the .=.trainer, Fig. .3 'WhiChfiS so :mechanicallyfmounted that it may be made :to assumeiany attitude that the actualvplaner would:

in'ifli'ght" bylmanipulation of :th'e rcontrols:i-. The: -5

rheostat 60 is mech'anically oonnectedi to z. the 1 trainer so thatias .theinose'i'of :thetrainer is: tilted upwardly -in response to its: controls .to: simulate climbing; the resistance is increased: An increase in resistano'e' of I the"rheostat :60 "decreases; the: 49-' power input to the armature-:22 ofithe 1110130134 0 r which re'sults: in a? decrease :insxthe: speed-:of the motor and hence'a decreaseifimthetspeed;of-rota+ tion or the generatortarmature 25:f rThe:decrease in -the 'speed of th'e'generator resultsin :a decrease" being-proportional ito ztneivolta-ge, anrr-henceifor to;

a-decrease in -voltag'eltheinstruments will. show a lower" 'air' speed: it l'onsth'etiothe'r hand; the nose Y of the trainer is tipped down in response tothe controls and at a" constantithrottlezthere will :be

an increase in "air 'speedf. In therar'rangementde-* 55,.

scribed, an increase inithe airspeedzwillshow upionith'e instruments i42;:-;44'-: and 45 .:due to: the fact that when' 'th'e'"trainer tipsidowrr thesresistw ance in the rheostat will automatically be-* de'creasedllience increasing tthe-spowen input 'rto 60- theiarmature" 22 increasing the speed'of: the generato'r [2, thefamourit of'voltage? output iromthe armature 25 anad hence supplyingea-nrin-a creased voltage'to the: instruments." This resultsrinan increase-inrthe air speedreading. As

the tilt dfthe plane" upwardlyror downwardly: in creases, the-"airspeed? instruments will showgreaterrand greater"speedchangeavhich will warn the pilot that *he" must maneuver the" controlsto keepi'fronr going :il'ltO adiver'on'a :spin which. 70.

change in the air"speedfinstruments:whichswilli 16:

'4 assist the pilot in quickly gaining a knowledge of the attitude of his plane solely with reference to his air speed instruments, and hence will give him training in blind flying.

It is also desirable to have the instruments responsive as they would be in actual. plane flight to "changes inthe throttle openings of the engines, that is, an increase in throttle opening at a constant level of night should show an increaseinairlspeed,.while for a decrease in throttle opening there should be a decrease in air speed, -Hence, there is also connected in series witlilthe'armature 22 by way of conduits 48 and 56, 'a pair of rheostats 52 and 54 in parallel, the resistancesof which may be varied in accordance with the throttle opening of the engines which they simulate. The resistances are varied by simulatedilthrottle:handles T and TI connected to the -rheostats' asshown in Figs. 2 and 3. As illustrated herein, if the trainer is being operated-.Lunder:'conditionsk simulating both engines runningfthe'twoiparallel connected rheostats 52 and" 54 will :be in the motor armature circuit I and so connected therein that their'resistances may'ibe-"variedbyithe' operation of the levers in th'eT-ground; trainer. :whichsimulates the throttle levers in. aplane As.:illusmrated, switches 5 l and 53aareprovided-"which are thrown to simulate conditions :when the'engines are-running to cause the? current :to'. pass. through .thevariable sides of i the 'rheostats 52 and :54 and z the variable sides arev directly -actuated-;to .varythe. resistances. bythe.:thrott1econtrol levers in the ground. trainer, the throttle control leversbeing operatedin syn: chronism to simulate synchronously operable: engines: Whenithe. throttle openings are increased: the resistances are decreasedandahence the power input to :themotor :I'G-is-increased, and as the generator.speedrincreases the :voltage output of the generator: increases and the instruments -42,- 44'and'4fishowanincrease-inair;speed. If, how-- ever; thethrottles are decreasedgthe resistances are automatically increased with the result that 1 the: air speed instruments show a decrease in air speed. As placed in the circuit, totalre sistances. of the rheostats 52 :and. 54 equal ,the reciprocal ofthe. sum .of :the reciprocals :so that. the" acceleration and deceleration effects of an: actual airplane will. beclosely; approximated; bothengines being synchronously operated;

In other words, with switches-;,5l and 53 in'the positions:.showniniull lines iini-Fi'gs. 1 and-.2 to; simulate the conditions WiGhibOth: engines-rune ning, the total resistanceprthesparallel circuit is -equal to one half ;of:the:resistance :in .each. leg thereof: Any. variation in 1 the positions of r the throttle control levers, which are: synchronously operable, will alter the: amount .of resistance ineach leg; equally, and will therefore proportionally alter the poweriinput. to;motor.-l 0 witha cor.- responding alteration in the readings of instruments; 44 and146:

While .the :operation of; the; air .speed instru: ments have been described; thus far iorgsimplicity with. an assumptionof constant throt: tleopeninglor constantlevel. flight, it is tobe. observed that an actual planewillnot be operated under such conditions all of the time but in flight will varyin attitudejand throttle simultaneously, so that any increase-in the reading of. the air. speed instruments. will. depend upon, acombination .of. attitude: and throttle opening, Actual iiightzconditionsrwill be simulatedin the traineryandwill register :in the-instruments; by meanst ofrthe." factxthatthey' will:respond-.to the;

amount or voltage impressed on them which in I Not infrequently, if-there is more than one en gine in the plane one of the engines will be stopped through failure of the same, or for some other reason, and in order to acquaint the pilot with the behavior of the air speed instruments under theseconditions, and also when both enginesare stopped if for instance in a glide, the rheostats 52 and 54 are so arranged that by throwing the switches and 53 to the dotted line position the whole resistance of these rheostats may be cut into the circuit. This decreases the power input to the motor Ill, and hence results in a decrease in air speed which simulates stopping one or both of the engines. The switches 53 and 5| are automatically thrown from one position to the other by a pair of electromagnet relays 64 and 66, respectively. The electromagnet relays are supplied with current from a 110-v. direct current line 68 and are automatically energized by way of leads I2 and 14 when the simulated engines in the trainer are started or stopped, means being provided in the trainer for simulating starting or stopping the engines. When both engines are running, the electromagnets oi the relays 64 and 66 are energized and operate to throw the switches 53- and 5| to the full line positions and hence to the variable sides of the rheostats so that the resistance may be varied with variations in the throttle opening. When the simulated engines are stopped, the relays will become deenergized and the switches 51 and 53 will be thrown to the dotted line position to cut in the entire resistance of the rheostats 52 and 54. It is evident that either or both engines may be running or stopped.

It is desirable to be able to cut out the armature circuit of the motor Ill which includes rheostats 52 and 54 and 60 so that the instruments 42, 44 and 46 do not respond to the attitude of the plane or throttle opening for example, when the plane is merely taxiing or any other period selected by the instructor, hence there is provided a cut out for the circuit during this period. As illustrated herein, this is made possible by a switch preferably located on the instructors desk. in the supply line 68, movementof switch 10 to the dotted line position shown in Figs. l and 2 acting to break the circuit from the line 68 toits ground 32. By breaking the circuit, an electromagnet relay 16 also in the line 68 is deenergized whichallows a switch 50 in the motor armature circuit to open. The switch 10 is held open while the trainer is still supposedly on the ground or water so that the instruments 42, 44 and 46 indicate no reading. Before the plane leaves the surface of the water or the ground, that is, during the run from standstill to take off, the plane lags in its response to its controls and hence the air speed instruments respond differentially. To simulate this lag, a rheostat 30 having a variableresist ance is placed across the armature circuit of the generator. As the air speed of the trainer increases, in a simulated take off and climb, this resistance is manually increased by the instructor to cause the air speed instruments to show an increase in air speed reading which corresponds to that of an actual plane as it takes off. At stabilized speed, the resistance in the rheostat 30 is cut out by movement of the contact point over onto the tab 3| and the armature circuit governs the flying conditions of the train or in simulated flight. A resistance 28 is placed in the armature circuit of the generator adiacent to the rheostat 30 to regulate the current flow, and hence to avoid complete short circuiting.

During take off and landing, the floats or landing gear present considerable air resistance and hence retard the speed of a plane for a given throttle opening. To simulate this condition in the ground trainer, there is inserted across the armature circuit of the generator, a resistance 38 which may be cut into and out of the circuit by a switch 40. Actuation of the switch will load the circuit, thereby causing the instruments to show a lower air speed and hence to simulate an extended position of the landing gear or floats, or unload the circuit thereby causing the instruments to show a normal air speed for a given throttle opening, and hence to simulate a retracted position of the landing gear or floats.

In operation, the student pilot and co-pilot after seating themselves in the ground trainer, start the simulated engines and proceed to operate the controls to make a simulated take off. At this time they watch their respective air speed instruments, and the instructor who observes the third instrument manually varies the rheostat 30 to simulate the air speed increase during the take off period up until stabilized flight condition is attained, whereupon the resistance 30 is cut out. During the run from rest to take off, the extended position of th landing gear or floats automatically openate to hold the switch 40 closed so that the resistances of the landing gear or floats is evident, and is reflected in the instrument by a lower air speed than would normally be indicated for the given throttle opening. As the plane rises from the ground and begins to climb, the pilot or co-pilot operates the controls to retract the landing gear or floats which opens the switch 4|]. From then on the instruments are controlled by the attitude of the plane, by the throttle openings, and by the operation of the engines to simulate an increase or decrease in the air speed of the plane in accordance with any combination of variations in'these controls. The instrument for the copilot gives th co-pilot an opportunity to study the response of the plane to-the pilots manipulation of its controls and thereby to learn by the. mistakes of the pilot, while the instructors instrument, which is not necessarily in the ground trainer itself, but may be placed on a tabl or desk near the trainer, enables the instructor to determine just what mistakes the pilot is making, so that he may be instructed as to how to correct his flying technique.

The invention described herein may b manuf-actured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. In a ground trainer for airplane pilots, means simulating the control of a pair of engines, simu lated air speed indicators, a motor generator combination, means connecting said indicators to the output side of the generator, said indicators being calibrated to indicate a change in air speed which is proportional to the voltage'in the output side of the generator, resistances in the motor circuit for reducing the output of th generator and relays associated with said resistances, said relays beingoperable in response to actuation of the first-mentioned means to a position simulating prri snti ieen iees i5 hrew a ii e r tate tothemieeeireei In a rer edrtra e Jon airplane .p11ot simulatedyairi speedindicat onla motors 8 56? combination, means connecting said air speed indicator to the output side of .thegeneratol, said thein rtion f.

" dicator to the output. sidebf. it iejefne ator; said airspeed.indioatorlbeing,calibrated to indicate,

afihahgein airspeed whichfis Proportional to the voltageLin the output side of the generator, a variableresistance in the motor circuit forvarying .the. input. to the. motor and hence the output of the generator,.means for automatically vary:

ing the variable-resistancein accordancewith the attitudeof .the.trainer...to siniyla e flight condir tions, and meansto,.cutthe variable resistance.

outv of the motorlcircuit.

3...In a g oundtrainer.fora rplanqP lo s, ans

simulating 'on andofr controls for engines, means; operable, to simulate opening and closing the engine. throttles, simulated air speed indicators, a motor generator combination, means connecting the air speedindicators,to theoutput side of the generatoix saidair speed indicators being. .calibrated to indicat change in the air speed which is proportional to the voltage in the output side of the generator, and ayariableresistance in the motor. circuit for each of the engine throttle control simulating means saidreSistanCes being variableby the throttle,simulatingmeans and impressed in their entirety in the motor circuit when said engine on and off controls simulating m ns r mean we f tq ii pm 4. In groundtrainer for aircraft pilots having controls. for changing th attitude of the trainer, means simulatingon and off controls for anengine an d alever operable to simulate opening and closing theengine throttle; simulated air speed indicators, a motor generator combination, means connecting the air speed indicators-to the output side of the generator, said instruments being calibrated toindicatea change in air speed Which-is proportional to. the voltage in the output side of thegenerator, andv variable resistances in the motor circuit, one of said resistances being automatically. variable with a change in attitude of th trainer, and. theother of said resistances being. variable in response to the actuation. of the lever, said last named resistance bein-gadapted to beimpressed in its entirely in the motor circuit by actuation of the engine on and ofigcontrols simulatingmeans to off position.

5-. In a groundtrainer for aircraft pilots, a simulated air speed indicator, a motor generator combination, means connecting said indicator to the output side of the generator, said indicator being calibrated to indicate a change in air speed which is proportional to the voltage in the output side ofthe generator, a variable resistor in the motor circuit, means responsive to the attitude of thetrainer for automatically varying said resistor, and means including an electro-magnetic switch operable for cutting out the. motor armature circuit to simulate the effect on air speed of alanding of the trainer.

6. In a ground trainer for aircraft pilots, a simulated air speed. indicator, a motor generator combination, means connecting the air speed indicator to the output side of the generator, said airspeed indicator beingcalibrated to indicate a change in speed which is proportional to the voltage in the output side of the generator, a resistance insertable in the output side of the generator to put aload ontthe generator, said resistance beingadapted tosimulate the eiiect on the aircraft air speed'dueto. the air resistance ofieredb the lowering of landing. gear .inrfiight prior to landou put, for op ra ion rt e-ri 'fi L ii i l idl ,variable resistali elifi i fietii itp i i .siii pilthe 8 4 ,stabilizationhas beeiilatt air. speed indicator 'bei ti0ns,,.a ,variable resis an the generator, said Ire air speed indicatorjbeing calibratedto indieatea f changein air speedlwhi fr, voltage .fin' .th'e ,odtput slde of the ,g'eiieratqh. a H

erator,.'manual, meanslfonvarying the resistance. during .lthe s'iinulat'ed take off andfclimb of the. planefto .stabilized iflight fl'co di ons, and means; for cutting said resi anc i at or ci cuitwnen 1 8. lnla grou'nd' ;trainer. .fqr a rplan pilots, a simulated airspeed indicator, a. motor generator. combination means co dicatorv to the ,output 1d" change in. airspeed, wh h voltage outputfof said e sistance 'in' the. inotor; circuit ing'.variable inaccord nce fl ght. CQ ldi hfii mlit i e Of insj m ua ly L variable in. accordance w th th conditions inc'i-f 1 dent to'the. kebifian thelc mb hemes? to stabilizedflighfi conditionsand rneans iorcutf A i 1 6 9.1

erator,}a source orlpotential np'ut connected to theimotor. armature, I I resistanceinfthe motor armaturej.,circuit an auto trolled'in response to the attitu to increase the speed ofthe v Y and. thereby the air. ,speedfin cationsgsiinultaneously ."on'nallindicators f with a.'.decrase in the angleloi attack, and viceve'rsa, anda rsiStanc andswitchllin. series, connectedjac'ross. the, gong erator. output, for operation by. the ipilotj as a) simulatedlilanding. gear. Tre'lfase when closed. to reduce th air 's pe'edyindicatifons .by an amod'nt. simulating the r'eductionjiiiairspeeddiie to air l resistance Tcaus'e the 10.; In a ground-tr ii'lfor airp1ane. pilots, a.

50s motor-generator ifriula''t'ed' airspeed ihdif I cators mpl'inected. acrossfthe' outputlfo'f saidgeiilorator, a source oi potential" input con'necte'dsto. the motor armature, aj' ariable resistance memes i With said source and qarnatureana automate:

cally controlled in respons o th attitude 'of s'a'id trainerto i ary the speed the motor-generator; unit and thereby the air an d indications siniiiI-I' taneously on all indicator .1nve r sely with-"the variations in the angle of attack, aresistanc e andf switch in series, connected ross the generator din ear ele se. when rlqsedfio r du e the air peed n cat onsbren amount mulates. he r ducti n in a r s ee -a mo. a r s ance caus d byv the .landinei eau and. ..va i. e: sistance. across .the, generator output for control, by the instructor toval-Tythespeed indications to: simulate air. speed;v aos s-;du. ne. ake-offer landing...

11.. In. a ground, trainer. for ai la e p lots, a motor-generator unit, simulated, air speed 'i n d i cat r c nnec ed. a r s zth. Q tputef idg t-j. eratona l i ienti 1..- nm t onnected to. e. motor rmature. ar able. si tanc in serieswith saidsource-and, said armature and;

automatically controlled in response to the attitude of said trainer to vary the speed of the motor-generator unit and thereby the air speed indications simultaneously on all indicators inversely with the variations in the angle of attack, a resistance and switch in series, connected across the generator output, for operation by the pilot :as a simulated landing gear release when closed to reduce the air speed indications by an amount simulating the reduction in air speed due to air resistance caused by the landing gear, a variable resistance across the generator output for control by the instructor to vary the speed indications to simulate air speed changes during take-off or landing, and a pair of variable resistances in parallel in the motor armature circuit, having sliding contacts for operation by the pilot as twin-engin throttles, switches for normally breaking said contacts to include the full resistances in the parallel branches to simulate dead 2 engine operat1on, and individual controls for opero ating said switches to simulate operation of either one or both engines and make throttle operations effective.

12. In a ground trainer, the combination defined in claim 11 having a switch cut-ofi means in th motor armature circuit for control by the instructor.

CLAUDE K. WILKINSON. REEVE C. MOREHOU'SE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,099,857 Link Nov. 23, 1937 2,280,117 Crane Apr. 21, 1942 2,366,603 Dehmel Jan. 2, 1945 2,442,205 Kail May 25, 1948 FOREIGN PATENTS Number Country Date 560,462 Great Britain Apr. 5, 1944 519,961 Germany Mar. 6, 1931 596,883 Germany Mar. 12, 1934 

